#include <stdio.h>
#include <unistd.h>
#include <netinet/in.h>                                                                   
#include <arpa/inet.h>
#include <netdb.h>    
#include <sys/wait.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <stdlib.h>
#include <time.h>
#include <string.h>

#define MAXLINE 200
#define RIO_BUFSIZE 8192

typedef struct{
    int rio_fd;
    int rio_cnt;
    char *rio_bufptr;
    char rio_buf[RIO_BUFSIZE];

}rio_t;

typedef struct sockaddr SA;

typedef struct{
int tm_sec;
int tm_min;
int tm_hour;
int tm_mday;
int tm_mon;
int tm_year;
int tm_wday;
int tm_yday;
int tm_isdst;
}tm;

void sigchld_handler(int sig){

    pid_t pid;
    int stat;

    while((pid = waitpid(-1,&stat,WNOHANG))>0){
        printf("child %d terminated\n",pid);
    }
    return;
}

int main(int argc,char **argv){

    int listenfd,connfd,port,clientlen;
    struct sockaddr_in clientaddr;
    struct hostent *hp;
    char *haddrp;
    char sbuf[MAXLINE];
    char rbuf[MAXLINE];
    rio_t rio;
    time_t lt;
    tm *local;
    char str1[MAXLINE]="客户端IP:";
    char str2[MAXLINE]="服务器实现者学号:";
    char str3[MAXLINE]="当地时间:";


    if(argc != 2){
    
        fprintf(stderr,"usage:%s <port>\n",argv[0]);
        exit(0);
    }

    port = atoi(argv[1]);

    signal(SIGCHLD,sigchld_handler);
    listenfd = open_listenfd(port);
    while(1){
    
        clientlen = sizeof(clientaddr);
        connfd = accept(listenfd,(SA *)&clientaddr,&clientlen);

        hp = gethostbyaddr((const char*)&clientaddr.sin_addr.s_addr,
                sizeof(clientaddr.sin_addr.s_addr),AF_INET);
        haddrp = inet_ntoa(clientaddr.sin_addr);
        printf("server connected to %s (%s)\n",hp->h_name,haddrp);

        if(fork() == 0){
        close(listenfd);
        lt = time(NULL); 
        local = localtime(&lt);
        strftime(sbuf,64,"%Y-%m-%d %H:%M:%S",local);
        send(connfd,sbuf,MAXLINE,0);
        close(connfd);
        exit(0);
        }

        close(connfd);
    }
}